Semiconductor processing typically requires several stages of surface etching and layer depositing to form circuits thereon. One device used to perform such etching and depositing is known as a microwave-induced plasma remote processor. With a remote processor, a metallic box is placed around a quartz tube or waveguide, and microwaves are generated therethrough by a magnetron. A gas is pumped into the quartz tube and excited into a plasma state therein by the microwaves.
The plasma is then directed from an outlet of the reactor to the surface of the semiconductor wafer being processed. The flow of the plasma from the outlet of the reactor to the semiconductor wafer tends to be nonuniform since there is no device to directionalize or distribute the plasma. Due to this nonuniformity, various portions of the wafer may be etched or deposited at different rates which can create defective circuitry.
One device typically used to attempt to provide a uniform flow distribution of the plasma from the reactor to the wafer is a disk placed there between. The disk may have holes passing there through to assist in the distribution of the plasma to the wafer. Unfortunately, the disk is also an object blocking the path of the radicals needed to process the wafer.
Thus, with the use of such a disk, some of the radicals may lose their reactivity and therefore be unable to process the wafer. Additionally, the disk material may act as a source of contamination to the processing of the wafer. Since the disk is positioned in the path of the plasma, portions of the disk may be etched by the plasma and redeposited on the wafer, thus contaminating the disk. Thus, there is a need for a method and apparatus for providing a uniform flow distribution in plasma reactors, without interferring with the plasma or causing undesirable contamination of the wafer being processed.